NLK Project EA 2860: EcoSmart Concrete Project Metakaolin Pre-Feasibility Study

This report is an appendix to the EcoSmart Project s Metakaolin Study. The report presents the results of NLK s metakaolin pre-feasibility review of the potential for developing metakaolin from the oil sands operations for use in concrete as a supplementary cementing material. The report covers the technical economic and environmental aspects of recovering and converting kaolin to metakaolin and of using metakaolin as a SCM.

The report concludes that metakaolin produced from the oil sands tailings is comparable to silica fume as an additive and is about 85-90% as reactive as commercially available metakaolin. It is technically viable for use as an SCM in concrete although its slight colouration precludes some uses. A precondition to considering the viability of extracted metakaolin is that it can be supplied at a low enough cost to provide economic benefits to ready mix concrete suppliers with resulting demand that it is adequate to justify an extraction plant.

Technical Report Author: NLK Consultants Inc.

Metakaolin Study: Pre-Feasibility Review of the Potential for Developing Metakaolin from Oil Sands Operations for Use in Concrete

This report evaluates the potential of metakaolin recuperated from oil sands tailing ponds in North Alberta as a supplementary cementing material -SCM- for concrete. Oil sands operations produce vast quantities of tailings containing extremely fine clays that prevent the reuse of process water from the tailings ponds. Preliminary research has indicated that this fine material can be processed into a product similar to metakaolin -MK- . Metakaolin is a valuable product with many commercial uses including as a high performance SCM. Extracting the fine clay from the ponds to produce SCM would have two benefits: clarifying the process water for reuse in the operations while producing a valuable product from a by-product.

The study finds however that while it is technically feasible the concept is uneconomical for many reasons. The material that can be produced from the pond – called calcined mature fine tailings or CMFT – while similar to MK has lower quality and performance than the products currently on the market. Another shortcoming is that CMFT is grey while metakaolin from virgin kaolin is white. Therefore in performance and appearance CMFT cannot compare to MK. Rather it is more like fly ash -FA- another SCM abundantly available in Alberta but at a much lower price than MK. Furthermore the oil sand region is isolated landlocked and far from the market for concrete. Because of the cost of extracting drying calcining and transporting the material CMFT cannot compete against FA and the study concludes on the non-feasibility of the concept. The oil sand industry still wants to resolve its water and pond issues and continues to investigate ways to process the fine tailing. If this research is successful and CMFT with improved quality color and cost can be produced then it will be worthwhile to reexamine the case and see if the product can be used in concrete.

Technical Report Author: EcoSmart Concrete Project

Concrete Incorporating Rice-Husk Ash: Compressive Strength and Chloride-Ion Penetrability

This report deals with the evaluation of the performance in concrete of an Indian sample of rice-husk that was burnt in an industrial furnace in Ontario and ground at the CANMET laboratories. This exploratory study was performed under contract with DCR Phoenix Development Corporation Ltd. Ottawa and is divided in two parts.

The first part deals with determining the optimum grinding time of the RHA in order to produce a highly-reactive product with a minimum energy of grinding. The performance of the RHA in concrete forms part II of the study. The results show that the rice-husk ash sample used in this study is principally composed of SiO2 -90.7 %- contains 4.7% loss on ignition and a relatively high K2O content of 2.2 %. The RHA ground for the optimum grinding time -140 seconds in a pulverizer with a capacity of 30 g- has a median particle size of ~ 8 µm a water requirement of ~ 104% and a pozzolanic activity index of ~ 100% in the mortar used for determining the pozzolanic activity of the RHA. The results also show that in general for similar W/CM -0.40- the replacement of 7.5 to 12.5% of the portland cement by the RHA did not affect significantly the compressive strength but improved significantly the resistance to the chloride-ion penetrability of the concrete with and without the entrained air.

Includes tables and figures detailing the study results.

Technical Report Author: Nabil Bouzoubaa, Benoit Fournier

Mechanical Properties and Durability of Concrete Made With High Volume Fly Ash Blended Cements Using a Coarse Fly Ash

This paper presents a study on the mechanical properties and durability of concrete made with a high-volume fly ash blended cement using a coarse fly ash that does not meet the fineness requirement of ASTM C 618. The results were compared with those of the HVFA concrete in which unground fly ash had been added at the concrete mixer. The properties of the fresh concrete determined included the slump air content slump loss stability of air content bleeding and setting time; those of the hardened concrete investigated included the compressive strength flexural- and splitting-tensile strengths Young’s modulus of elasticity drying shrinkage resistance to abrasion chloride-ion penetration freezing and thawing cycling and to de-icing salt scaling. The results show that except for the resistance of the concrete to the de-icing salt scaling the mechanical properties and the durability of concrete made with this blended cement were superior to the concrete in which the unground fly ash and the cement had been added separately at the mixer. The production of HVFA blended cements therefore offers an effective way for the utilization of coarse fly ashes that do not otherwise meet the fineness requirements of ASTM C 618.

This paper was originally published in Cement and Concrete Research Vol. 31 No. 3 Oct. 2001. It includes a list of tables and figures detailing the results of the studies.

Technical Report Author: M.H. Zhang, Nabil Bouzoubaa, V.M. Malhotra, CANMET Energy Technology Centre, Natural Resources Canada,

Development of Ternary Blends for High-Performance Concrete

The purpose of this study was to develop ternary blends with optimum amounts of fly ash and silica fume to be used in high-performance concrete. Two series of air-entrained concrete mixtures were investigated in the study: series 1 included concretes with a total cementitious materials content -CM- of 350 kg/m 3 and a water-to-cementitious materials ratio -W/CM- of 0.40 and series 2 included concretes with a total CM of 450 kg/m 3 and a W/CM of 0.34. In each series one silica fume and three fly ashes were used; these consisted of two ASTM Class F and one ASTM Class C fly ashes. Properties of the fresh and hardened concrete such as slump air content bleeding setting time autogenous temperature rise plastic shrinkage compressive strength drying shrinkage and the resistance to chloride-ion penetration were determined. The results show that the combined use of fly ash and silica fume in concrete are more advantageous in terms of the following parameters: the dosage of superplasticizer plastic shrinkage chloride-ion penetrability and the drying shrinkage. The report includes various tables and figures detailing the results of the study.

Technical Report Author: Nabil Bouzoubaa, Alain Bilodeau, Benoit Fournier, V. Sivasundaram, D.M. Golden, CANMET Energy Technology Centre, Natural Resources Canada,